The instant invention relates to methods of treating water and more particularly to an effective method of treating water to kill substantially all of the bacteria therein.
It is well recognized in most developed countries that water must be effectively treated to kill various micro-organisms therein, such as bacteria, before it can be utilized in municipal water systems. It is further generally recognized that water must be effectively treated before it can be utilized in swimming pools, hot tubs and spas, particularly when the pools, etc. are used by segments of the general public. In this regard, it is well recognized that bodies of water, such as swimming pools, hot tubs and spas are highly susceptible to rapid micro-organism growth and that they can rapidly become extremely hazardous to users thereof unless the water is effectively and continuously treated against micro-organisms.
It is also well known that the most common method of treating water against micro-organisms to render the water safe for human consumption and/or use in swimming pools, spas, etc. is to add chlorine (normally is the form of a hypochlorite salt or chlorine gas) to the water. However, it has been found that not only does chlorine have an objectionable odor, but that it can also cause skin irritations and serious eye irritations to users of pools, spas, etc.
Because of the objectionable physical properties of chlorine a number of alternate water treatment systems which operate without chlorine have been developed in recent years. One of the most effective types of alternative water treatment systems is a system in which silver ions are added to water to kill bacteria therein. In this regard, the applicant's prior U.S. Pat. No. 4,608,247 discloses an exemplary system of this general type. However, it has been found that in many cases systems of this type are only partially effective, and that often times reduced amounts of chlorine must nevertheless be added to water treated by such systems.
The instant invention provides an effective new method of treating water against micro-organisms including bacteria. More specifically, the instant invention provides an effective method of treating water to essentially instantaneously kill virtually all of the bacteria therein without the use of significant amounts of chlorine or other objectionable chemicals. Still more specifically, the instant invention provides an effective method of treating water by generating an active oxidizer in the water which is capable of attacking and killing a wide range of microorganisms therein. Even still more specifically, the instant invention provides a method of treating water comprising exposing the water to a silver catalyst in the presence of oxygen to form an active oxidizer in the water and, in some instances to also release silver ions therein via an erosion process similar to that set forth in the applicant's aforesaid prior U.S. patent. The water and the silver catalyst are, however, preferably maintained substantially free of compounds, such as activated charcoal or manganese dioxide, which would accelerate the degradation of the active oxidizer in the water. Accordingly, when an erosion buffer of the general type described in the applicant's aforesaid prior-U.S. patent is called for, a relatively inert material, such as PVC, is used rather than activated charcoal. The silver catalyst utilized in the method comprises an alumina matrix having between approximately 0.1% and 5% by weight of elemental silver chemically deposited thereon. The matrix has a surface area of at least approximately 50 m.sup.2 /gm and the matrix with the silver thereon is heated to between approximately 300.degree. C. and 1050.degree. C. prior to use in the method. The oxygen utilized in the method preferably comprises ozone, although it can alternatively comprise O.sub.2 which is present at a level of at least 2 ppm and at least 50% of the saturation level of the O.sub.2 in the water. The silver catalyst is preferably heated to a temperature of at least approximately 750.degree. C. prior to use in the method, and theoretically the elemental silver preferably includes at least 2% of silver crystals having crystal sizes between approximately 3 nanometers and 10 nanometers or crystal sizes in excess of 1000 nanometers. The water which is treated by method is preferably exposed to the silver catalyst at a rate of between 0.1 ml and 0.5 ml of water per minute per square meter of catalyst surface. In the basic form of the method the active oxidizer in the water comprises either elemental oxygen on the surface of the silver catalyst or hydrogen peroxide in the water. In a second form of the method, an oxidizable salt selected from a group consisting of a bromide, a chloride, an iodide, a metasulfate or a metaborate is added to the water. Accordingly, in the second form of the method oxidized ions of the salt are formed as an active oxidizer as the water is exposed to the silver catalyst.
It has been found that the method of the instant invention can be effectively utilized for treating water in order to kill various micro-organisms contained therein. Specifically, it has been found that virtually all bacteria contained in water treated by the method of the subject invention are instantaneously killed so that the water is immediately rendered safe for human consumption and/or for use in pools, spas, etc. It has been further found that when a low and unobjectionable level of a salt of the type specified is added to water prior to the treatment thereof by the method, the salt is converted to a safe and effective active oxidizer which is relatively stable under most conditions so that it has a prolonged beneficial effect with respect to maintaining the bacteria level in the treated water at a safe level.
Accordingly, it is a primary object of the instant invention to provide an effective method of treating water to kill micro-organisms, such as bacteria, therein.
Another object of the instant invention is to provide a method of treating water for pools, spas, etc. without the use of chlorine.
An even still further object of the instant invention is to provide a method of forming an effective active oxidizer in water which can kill most bacteria therein.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds herein.